package org.apache.lucene.util.packed;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**     
 * Implements {@link PackedInts.Mutable}, but grows the
 * bit count of the underlying packed ints on-demand.
 *
 * <p>@lucene.internal</p>
 */

public class GrowableWriter implements PackedInts.Mutable {

    private long currentMaxValue;
    private PackedInts.Mutable current;
    private final boolean roundFixedSize;

    public GrowableWriter(int startBitsPerValue, int valueCount, boolean roundFixedSize) {
        this.roundFixedSize = roundFixedSize;
        current = PackedInts.getMutable(valueCount, getSize(startBitsPerValue));
        currentMaxValue = PackedInts.maxValue(current.getBitsPerValue());
    }

    private final int getSize(int bpv) {
        if (roundFixedSize) {
            return PackedInts.getNextFixedSize(bpv);
        } else {
            return bpv;
        }
    }

    public long get(int index) {
        return current.get(index);
    }

    public int size() {
        return current.size();
    }

    public int getBitsPerValue() {
        return current.getBitsPerValue();
    }

    public PackedInts.Mutable getMutable() {
        return current;
    }

    // @Override
    public Object getArray() {
        return current.getArray();
    }

    // @Override
    public boolean hasArray() {
        return current.hasArray();
    }

    public void set(int index, long value) {
        if (value >= currentMaxValue) {
            int bpv = getBitsPerValue();
            while (currentMaxValue <= value && currentMaxValue != Long.MAX_VALUE) {
                bpv++;
                currentMaxValue *= 2;
            }
            final int valueCount = size();
            PackedInts.Mutable next = PackedInts.getMutable(valueCount, getSize(bpv));
            for (int i = 0; i < valueCount; i++) {
                next.set(i, current.get(i));
            }
            current = next;
            currentMaxValue = PackedInts.maxValue(current.getBitsPerValue());
        }
        current.set(index, value);
    }

    public void clear() {
        current.clear();
    }

    public GrowableWriter resize(int newSize) {
        GrowableWriter next = new GrowableWriter(getBitsPerValue(), newSize, roundFixedSize);
        final int limit = Math.min(size(), newSize);
        for (int i = 0; i < limit; i++) {
            next.set(i, get(i));
        }
        return next;
    }
}
